Method and system for multiple symmetric encryption for .ZIP files

ABSTRACT

The present invention provides a method of integrating existing strong encryption methods into the processing of a .ZIP file to provide a highly secure data container which provides flexibility in the use of symmetric and asymmetric encryption technology. The present invention adapts the well established .ZIP file format to support higher levels of security and multiple methods of data encryption and key management, thereby producing a highly secure and flexible digital container for electronically storing and transferring confidential data

BACKGROUND OF THE INVENTION

The present invention relates generally to a method of using standard .ZIP files and strong encryption technology to securely store files, and more particularly to a method of integrating existing strong encryption methods into the processing of .ZIP files to provide a highly secure data container which provides flexibility in the use of symmetric and asymmetric encryption technology. The present invention adapts the well established and widely used .ZIP file format to support higher levels of security and multiple methods of data encryption and key management, thereby producing an efficient, highly secure and flexible digital container for electronically storing and transferring confidential data

Compression of computer files has been available for many years. Compressing files can save large amounts of disk space, and can reduce transfer time when downloading files from the Internet or transferring files through email. Almost any file one downloads from the Internet is compressed in some way. A standard compressed file or folder as it is sometimes called contains one or more files that were compressed into a single file or folder. Many different compression formats have been developed over the years. The .ZIP format, created by the assignee of the present invention, is perhaps the most common compressed file format for the personal computer. Any file with a “.zip” extension most likely contains one or more files of data archived, that is, each either compressed or stored, in the .ZIP format. “Zipping” a file has become a commonly used term meaning to compress the file into the .ZIP format archive so that it occupies less disk space, and similarly, “unzipping” a file means decompressing a compressed file in the .ZIP format.

A .ZIP file is generally recognized as a data compression and archiving format invented by PKWARE, Inc. The .ZIP format is a file format designed for combining data compression technology with file archiving techniques. Many commercially available software products are available for compressing or “zipping” files or other data into the .ZIP format. These .ZIP files can then be used to reconstruct the original data through the “unzipping” process. Data compression converts the contents of a file into an encoded format requiring less computer storage space or in the case of transmission less network bandwidth than the original uncompressed file.

Archiving, in the context of a .ZIP file, is a method of storing information about the characteristics of a file in a catalogue of files, known as the Central Directory, inside the .ZIP file, allowing each file to be retrieved individually by its characteristics. This capability is widely used. These characteristics include, but are not limited to, file name, file size, and file creation date and time.

Software programs such as PKZIP® written by PKWARE, Inc. are used to process files in the .ZIP format. Such programs allow one or more files of any type to be compressed and archived into a file of the .ZIP format type for efficient file storage and transmission over computer and communication networks. This format and the software programs that process .ZIP files have become ubiquitous.

Data encryption is used by many software programs to provide data privacy. Data encryption is a method of encoding data so that it cannot be reproduced in its original form unless an associated key is provided. Decryption uses this key to convert the encrypted data back into its original state. The key is known only to the person encrypting the data or by those other people with whom the person encrypting the data chooses to share the key. The key is used to “unlock” the data so that it can again be used in its original form.

Keys are uniquely generated using data known to the person encrypting a file or other data associated with recipients and users of the file. This data can be a user-defined password or other random data. Several methods are commonly used for processing the keys used for data encryption. Encryption using a key generated from a password is an example of symmetric encryption. Encryption using a public/private key pair is an example of asymmetric encryption. An example of one method for processing encryption keys supported by this invention uses a public/private key pair commonly associated with digital certificates as defined by the document Internet X.509 Public Key Infrastructure Certificate and CRL Profile (RFC 2459). A digital certificate is a unique digital identifier associating a public and private key pair to an assigned individual, a group, or an organization. When used for encrypting data, the public key of an individual is used to process an encryption key which only the individual in possession of the corresponding private key can use for decryption. A digital certificate is issued to an individual, a group, or an organization for a fixed period of time and can only be used during this time period. After the time period has elapsed, the digital certificate will be considered to have expired and must be reissued for a new time period.

The strength of a data encryption method is determined at least in part by its key size in bits. The larger the key size a data encryption method uses, the more resistant it is to cryptanalysis. Cryptanalysis, or popularly “cracking”, is the unauthorized access to encrypted data. Strong encryption is a type of data encryption that uses key sizes of 128 bits or more. A number of encryption encoding methods are known today. Examples supported by the present invention include but are not limited to Advanced Encryption Standard (AES), Data Encryption Standard (DES), 2DES, 3DES, and others. A number of key sizes are commonly used today. Examples supported by the present invention include but are not limited to 128 bits, 192 bits, and 256 bits.

Many software programs available today that process .ZIP files use data encryption to encrypt files after compression as they are written to the .ZIP file. The data encryption method used by these software programs uses a key size of 96 bits or less and is considered weak or moderate encryption by today's standards. These software programs use keys generated using user-defined password data. Weak data encryption may not provide sufficient security to computer users that store and transfer their confidential data files using the .ZIP format.

Password-based key generation has been a commonly used method of applying data encryption, however, known vulnerabilities to cracking methods such as “brute force password cracking” make this method of encryption insufficient to meet today's more advanced security needs. Another known limitation of password-based security is the lack of non-repudiation. Non-repudiation is the ability to be certain that the person or program that created an encrypted .ZIP file cannot deny that fact and that their identity is bound to the .ZIP file they created. This cannot be achieved with symmetric encryption methods. Today, non-repudiation is an important aspect of security related to the implementation of digital certificates and digital signatures. It is critically important to be able to prove that a creator or sender of an encrypted file did in fact create the file, i.e. not repudiate his/her action.

Therefore, a need exists to extend the options for levels of security available to programs that process .ZIP files. This extended of security capability makes use of the encryption technologies available today or others that may gain acceptance in the future.

SUMMARY OF THE INVENTION

The present invention provides a method of integrating multiple strong encryption methods into the processing of .ZIP files to provide a highly secure-data container which provides flexibility in the use of symmetric and asymmetric encryption technology. The present invention adapts the well established .ZIP file format to support higher levels of security and multiple methods of data encryption and key management, thereby producing a highly secure and flexible digital container for storing and transferring confidential electronic data.

The present invention provides a method of integrating multiple strong encryption methods into the processing of .ZIP files to provide a highly secure data container which provides flexibility in the use of encryption technology. The present invention supports existing weak encryption methods available in .ZIP software programs used today to ensure backward compatibility with existing software programs that use the .ZIP file format. Strong encryption methods are made available to computer users as configurable options to select when compressing and encrypting their files or other data into a .ZIP file.

The method of the present invention provides the capability of using strong encryption when creating .ZIP files. It is flexible in that it provides that different encryption methods can be applied to a single .ZIP file to meet the security needs of a given computer user or application. Strong encryption algorithms are preferably used in conjunction with either password (symmetric) or any form of public/private key (asymmetric) encryption methods. The symmetric method preferably includes a password defined by the user, while the asymmetric method preferably includes a public/private key associated with digital certificates to process encryption keys. The invention allows one or more passwords and one or more public keys to be used individually, or in combination at the same time when archiving any file of any type of data into a secure .ZIP file. This capability is useful since secure .ZIP files are frequently distributed, or otherwise made accessible, to multiple recipients for decryption. Some of those recipients may require password access while others may require certificate access.

The method of the present invention also supports the four basic security functions to be associated with encrypted files: confidentiality, message authentication, sender or creator authentication, and non-repudiation.

Specifically, the present invention supports non-repudiation to uniquely bind a .ZIP file with the identity of its creator, and prevent that creator from denying the creation of that .ZIP file. One method of non-repudiation used by this invention is the identity support available with digital signatures that can be generated using public/private key technology. The non-repudiation function provided by the present invention also preferably supports time-stamping methods for fixing the creation of a digital signature in time, as well as time-stamped audit trails providing transaction history.

As indicated, the method of the present invention also supports message authentication. Message authentication ensures the data has not been altered since being encrypted. The present invention supports message authentication techniques that employ public/private key forms of message authentication, as well as other methods of message authentication that do not require the use of public/private keys. One example of an alternative method that does not use a public/private key is a cryptographic checksum.

The method of the present invention further supports the encryption of file characteristics for each file inside a .ZIP file. Current .ZIP software programs encrypt only the contents of the files in a .ZIP file. The additional characteristics for each file, such as its name, size, etc., remain unencrypted. To remove the possibility that this unencrypted data for a file could be made available to an unauthorized user, this information may preferably also be encrypted as an option. This additional encryption further increases the level of security available to .ZIP file users.

Public keys such as those associated with digital certificates used for encrypting .ZIP file data preferably resides on a user's local computer in a file or a database, on an external device such as a Smart Card or other removable device, or in a shared data repository such as a directory service served by an LDAP server.

The present invention also provides multiple methods of checking whether a digital certificate is valid for use. These methods preferably include, but are not limited to standard methods of certificate validation, such as searching certificate revocation lists (CRL), certificate trust lists (CTL), and online checking via the internet using Online Certificate Status Protocol (OCSP) or Simple Certificate Validation Protocol (SCVP).

The method of the present invention also preferably defines data storage locations within the established .ZIP file format specification for storing information on the encryption parameters used when a file was encrypted and on the keys needed when a file is to be decrypted. One such example of these data storage locations includes a field to identify that a new strong encryption method has been applied to a file in the .ZIP file. The strong encryption record will be defined within a Central Directory storage area for each encrypted file. The Central Directory is a storage location defined in the .ZIP file format which serves as a table of contents for the entire .ZIP file. An entry is made into the Central Directory for each file added to a .ZIP file. A decryption record will be defined for storing the information needed to initialize and start the decryption process. This decryption record will be placed immediately ahead of the encrypted data for each file in a .ZIP file. This example is not the only method of storing this data as other storage methods can be defined.

The present invention provides many advantages or benefits over the prior art. One benefit is the ability to use multiple encryption methods instead of supporting only a single encryption method. A second benefit is the ability to use a mixture of symmetric and asymmetric encryption in a single, secure .ZIP file. A third benefit is that the encryption of individual files using advanced public/private keys provides a significantly higher level of security to computer users. A fourth benefit is that encryption of .ZIP file data can be implemented using a range of commonly available cryptographic toolkits. A fifth benefit is that the present invention supports using packaged or readily available encryption algorithms to provide state-of-the-art security. A sixth benefit is the availability of non-repudiation using digital signatures through the use of public/private key technology. A seventh benefit is that the invention ensures a high degree of interoperability and backward compatibility by extending the current .ZIP file format.

Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the following detailed description, claims, and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a record layout of a prior art .ZIP file prior to the present invention.

FIG. 2 is a record layout of a .ZIP file in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIG. 1 shows the file format for the standard .ZIP file, in existence prior to the present invention. FIG. 2 illustrates the preferred general record layout of a .ZIP file in accordance with the present invention.

The newly modified .ZIP file format specification according to the present invention, as published by PKWARE, Inc., is described in a document entitled APPNOTE.TXT, which is attached hereto and incorporated herein by reference. The new version of the .ZIP file format provides an implementation of the use of strong encryption based on a key generated using a password. This implementation constitutes one example of a structure and layout of the records and fields suitable for processing secure .ZIP files as defined by the present invention. The complete description of the conventional or standard .ZIP file format will not be included here since this information is generally well known. Only the portions pertaining to the new records and fields defined by the new format, capable of storing data using strong encryption, will be discussed in detail.

The present invention extends the original .ZIP file format with the addition of new storage records to support the use of strong encryption methods including, as described above, both public/private key, or asymmetric, methods, and password-based, or symmetric, methods, and the capability to use a mixture of symmetric and asymmetric methods.

An example of implementing a new strong encryption method is discussed below. This example identifies several new records and fields that must be defined within the .ZIP file format.

-   -   A new General Purpose Bit Flag having a hexadecimal value of         0×0040 to be set in both the Local and Central Record Headers         when strongly encrypting a file.     -   A new Decryption Header to be located immediately ahead of and         adjacent to the compressed data stored for each file.     -   A new Extra Field record definition with an ID having a         hexadecimal value of 0×0017 to be inserted into the Central         Record Header for each file.

When using these new fields for strongly encrypting files, the following actions are indicated.

-   -   1. If the General Purpose Bit Flag value of 0×0040 is set to         indicate strong encryption was applied to a file, the General         Purpose Bit Flag value of 0×0001 will also generally be set.     -   2. Files having a size of zero bytes (an empty file) should not         generally be encrypted. As indicated, however, the file         characteristics of the archived files may be encrypted, even if         the file is of zero length and is not itself encrypted.     -   3. The contents of the field labeled Version Needed to Extract         in both the Local and Central Record Headers should preferably         be set to the decimal value of 50 or greater. If the AES         encryption method is used, the contents of the field labeled         Version Needed to Extract in both the Local and Central Record         Headers should preferably be set to the decimal value 51 or         greater.     -   4. Data encryption should preferably be applied after a file is         compressed, but encryption can be applied to a file if         compression is not used. If compression is not applied to a         file, it is considered to be stored in the .ZIP file.     -   5. If encryption is applied using digital certificates, a list         of intended recipients will be constructed. Each entry in the         recipient list identifies a person whose public key has been         used in the encryption process for a file and who is allowed to         decrypt the file contents using their private key.

Record Definitions: New Decryption Header (NDH) Size Value (bytes) Description IV size 2 Size of custom initialization vector/salt, if 0 then CRC32 + 64-bit File Size should be used to decrypt data. IV variable Initialization vector/salt (file specific) which should be used in place of CRC32 + 64-bit File Size Original Size 4 Original (uncompressed) size of the following data Decryption Info. variable Decryption Information

Description Information (details) Size Value (bytes) Description Version (3) 2 Version/Format of decryption information. AlgID 2 Encryption Algorithm ID BitLen 2 Bit length of the key Flags 2 Processing flags ERD size 2 Size of Encrypted Random Data (ERD) ERD variable Encrypted Random Data Recipient Count 4 Number of Recipients Hash Algorithm 2 Hash algorithm to be used to calculate Public Key hash (absent for password based encryption) Hash Size 2 Size of Public Key hash (absent for password based encryption) Recipient List variable Recipient List Element (absent for password Element based encryption) Password 2 Size of random password validation data Validation Data (Includes CRC32 of PVD; >4) MUST be size multiple of encryption block sizes Password, variable Password Validation Data (PVD) Validation Data CRC32 of PVD 4 CRC32 of PVD, used for password verification when decrypting data

Encryption Algorithm ID (AlgID) identifies which of several possible strong encryption algorithms was used for encrypting a file in the .ZIP file. The strong encryption algorithms that can be used include but are not limited to AES, 3DES, 2DES, DES, RC2 and RC4. The use of other unspecified strong algorithms for encryption is supported by the present invention.

Hash Algorithm identifies which of several possible hash algorithms was used for the encryption process for a file in the .ZIP file. The algorithms that can be used include but are not limited to MD5, SHA1-SHA512. The use of other unspecified algorithms for hashing is supported by the present invention.

Flags

The following values are defined for the processing Flags. Name Value Description PASSWORD_KEY 0x0001 Password is used CERTIFICATE_KEY 0x0002 Recipient List is used COMBO_KEY 0x0003 Either a password or a Recipient List can be used to decrypt a file DOUBLE_SEED_KEY 0x0007 Both password and Recipient List are required to decrypt a file. ERD is encrypted twice by 2 separate keys. DOUBLE_DATA_KEY 0x000f Both a password and a Recipient List are required to decrypt a file. File data is encrypted twice using 2 separate keys. MASTER_KEY_3DES 0x4000 Specifies 3DES algorithm is used for MSK

Recipient List Element Size Value (bytes) Description Recipient Element size 2 Combined size of Hash of Public Key and Simple Key Blob Hash Hash Size Hash of Public Key Simple key Blob variable Simple Key Blob

New Decryption Central Record Extra Field (NDCEF) Size Value (bytes) Description 0x0017 2 Signature of NDCEF Data Size 2 Size of the following data (at least 12 bytes) Version (2) 2 Version/Format of this extra field. AlgID 2 Encryption Algorithm ID. BitLen 2 Bit length of the key Flags 2 Processing flags Recipient Count 4 Number of Recipients Hash Algorithm 2 Hash algorithm to be used to calculate Public Key hash (absent for password based encryption) Hash Size 2 Size of Public Key hash (absent for password based encryption) Simplified variable Simplified Recipient List Element (absent Recipient List for password based encryption) Element

Simplified Recipient List Element Size Value (bytes) Description Hash Hash Hash of Public Key Size

A simplified recipient list element is defined as a subset of a recipient list element and is stored to provide redundancy of the recipient list data for the purposes of data recovery.

Process Flow:

The following is a description of the most preferred encryption/decryption process for a single file using the storage format defined by this example. Any programs, software or other processes available to suitably perform the encryption/decryption process may be used.

Encryption:

-   -   1. Validate public/private key     -   2. Calculate file digital signature and time-stamp     -   3. Compress or Store uncompressed file data     -   4. Generate a File Session Key (FSK) (see below)     -   5. Calculate Decryption Information size     -   6. Adjust Compressed Size to accommodate Decryption Information         and padding     -   7. Save Decryption Information to .ZIP file     -   8. Encrypt Compressed or Stored File Data     -   9. Encrypt file characteristics         Decryption:     -   1. Decrypt file characteristics     -   2. Read Decryption Information from .ZIP file     -   3. Generate FSK (see below)     -   4. Verify Decryption Information (see below)     -   5. If Decryption Information is valid, then decrypt Compressed         or Stored File Data     -   6. Decompress compressed data     -   7. Validate file time-stamp and digital signature         Generating Master Session Key (MSK)     -   1. If MASTER_KEY_(—)3DES is set, use 3DES 3-key as MSK         algorithm, otherwise use specified algorithm.     -   2. If encrypting or decrypting with a password.     -   2.1.1. Prompt user for password     -   2.1.2. Calculate hash of the password     -   2.1.3. Pass calculated hash as argument into a cryptographic key         derivation function or its equivalent.     -   3. When encrypting using a public key(s)     -   3.1.1. Call a cryptographic key generation function or its         equivalent to generate random key     -   4. When decrypting using a private key(s).     -   4.1.Using Recipient List information, locate private key, which         corresponds to one of the public keys used to encrypt MSK     -   4.2.Decrypt MSK         Salt and/or Initialization Vector (IV)     -   1. For algorithms that use both Salt and IV, Salt=IV     -   2. IV can be completely random data and placed in front of         Decryption Information     -   3. Otherwise IV=CRC32+64-bit File Size         Adjusting Keys     -   1. Determine Salt and/or Initializaton Vector size of the key         for the encryption algorithm specified. Usually salt is         compliment to 128 bits, so for 40-bit key Salt size will be 11         bytes. Initialization Vector is usually used by block algorithms         and its size corresponds to the block size.     -   2. If Salt size >0 or Initializadon Vector size is >0 then set         IV¹ to be used by the specified encryption algorithm.         ¹When adjusting MSK, if IV is smaller then required         Initialization Vector (or Salt) size it is complimented with 0,         if it is larger it is truncated. For all other operations IV is         used as is without any modifications.         Generating File Session Key (FSK)     -   1. FSK ←SEA1(MSK(IV)). Adjust MSK with IV, and decrypt ERD         (Encrypted Random Data). Calculate hash of IV+Random Data. Pass         calculated hash as argument into a cryptographic key derivation         function or its equivalent to obtain FSK         Verifying Decryption Information     -   1. Decryption Information contains variable length Password         Validation Data (PVD).     -   2. First Password Validation Data Size—4 bytes are random data,         and last 4 bytes are CRC32 of that random data. This allows         verification that the correct key is used and deters plain text         attacks.

The following modifications are used for encrypting and decrypting multiple files.

Multi-File Encryption:

-   -   1. Generate MSK     -   2. For each file follow Encryption steps.         Multi-File Decryption:     -   1. Generate MSK from the file Decryption Information     -   2. For each file follow Decryption steps     -   3. If Decryption Information verification fails go to step 1

Alternate storage formats can be defined for implementing the flexible security support within .ZIP files. One such alternative is to use other fields, either existing or newly defined to denote that a strong encryption method was applied to a .ZIP archive. Another alternative could be to use additional storage fields in addition to those defined in the above example, or to use the fields as defined, but ordered differently within each record. Still other implementations may use fewer, or more, records or fields than are defined by the above example or the records and fields may be placed in other physical locations within the .ZIP file.

Alternate processing methods can also be defined for implementing the flexible security support within .ZIP files. One such alternative is to implement the encryption process for each file using another public/private key technology such as that defined by the OpenPGP Message Format as documented in RFC 2440. Another alternative could be to use a more direct form of encryption key generation where the file session key is directly used for encrypting each file. This method would not use the indirect form described in the above example where the file session key is derived from a master key.

While the invention has been described with reference to preferred embodiments, it is to be understood that the invention is not intended to be limited to the specific embodiments set forth above. Thus, it is recognized that those skilled in the art will appreciate that certain substitutions, alterations, modifications, and omissions may be made without departing from the spirit or intent of the invention. Accordingly, the foregoing description is meant to be exemplary only, the invention is to be taken as including all reasonable equivalents to the subject matter of the invention, and should not limit the scope of the invention set forth in the following claims. 

1. A method of placing data in a .Zip file format data container, said method including: receiving a data file; generating a first symmetric key from random data; symmetrically encrypting said data file using said first symmetric key to form and encrypted data file; generating a second symmetric key; symmetrically encrypting said first symmetric key using said second symmetric key to form second symmetric key data; generating a third symmetric key; symmetrically encrypting said first symmetric key using said third symmetric key to form third symmetric key data; and placing said encrypted data file, said second symmetric key data, and said third symmetric key data in a data container, wherein said data container is constructed in accordance with a .Zip file format.
 2. The method of claim 1 further including: compressing said data file before symmetrically encrypting said data file.
 3. The method of claim 2 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.
 4. The method of claim 2 wherein said compressing employs a Deflate-type data compression algorithm.
 5. The method of claim 2 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 6. The method of claim 1 wherein said data file is not compressed before symmetrically encrypting.
 7. The method of claim 1 wherein at least part of one of said second symmetric key and said third symmetric key is composed of random data.
 8. The method of claim 7 wherein at least part of said second symmetric key is composed of a first set of random data and at least part of said third symmetric key is composed of a second set of random data.
 9. The method of claim 8 wherein said first set of random data is not equal to said second set of random data.
 10. The method of claim 1 wherein said at least part of one of said second symmetric key and said third symmetric key is received from a user.
 11. The method of claim 10 wherein said at least part of one of said second symmetric key and said third symmetric key is a password.
 12. The method of claim 11 wherein at least part of said second symmetric key is a first password and at least part of said third symmetric key is a second password
 13. The method of claim 12 wherein said first password is not equal to said second password.
 14. The method of claim 1 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 128 bits.
 15. The method of claim 1 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 192 bits.
 16. The method of claim 1 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 256 bits.
 17. The method of claim 1 wherein said symmetrically encrypting said data file uses an AES encryption encoding operation.
 18. The method of claim 1 wherein said symmetrically encrypting said data file uses a 3DES encryption encoding operation.
 19. A .Zip file format data container including: an encrypted data file, said data file encrypted using a first symmetric key, wherein said first symmetric key is generated from random data; second symmetric key data, said second symmetric key data generated from a second symmetric key used to symmetrically encrypt said first symmetric key; and third symmetric key data, said third symmetric key data generated from a third symmetric key used to symmetrically encrypt said first symmetric key, wherein said data container is constructed in accordance with a .Zip file format.
 20. The .Zip file format data container of claim 19 wherein said data file is compressed prior to symmetric encryption.
 21. The .Zip file format data container of claim 20 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.
 22. The .Zip file format data container of claim 20 wherein said compressing employs a Deflate-type data compression algorithm.
 23. The .Zip file format data container of claim 20 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 24. The .Zip file format data container of claim 19 wherein said data file is not compressed before symmetric encryption.
 25. The .Zip file format data container of claim 19 wherein at least part of one of said second symmetric key and said third symmetric key is composed of random data.
 26. The .Zip file format data container of claim 25 wherein at least part of said second symmetric key is composed of a first set of random data and at least part of said third symmetric key is composed of a second set of random data.
 27. The .Zip file format data container of claim 26 wherein said first set of random data is not equal to said second set of random data.
 28. The .Zip file format data container of claim 19 wherein said at least part of one of said second symmetric key and said third symmetric key is received from a user.
 29. The .Zip file format data container of claim 28 wherein said at least part of one of said second symmetric key and said third symmetric key is a password.
 30. The .Zip file format data container of claim 29 wherein at least part of said second symmetric key is a first password and at least part of said third symmetric key is a second password
 31. The .Zip file format data container of claim 30 wherein said first password is not equal to said second password.
 32. The .Zip file format data container of claim 19 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 128 bits.
 33. The .Zip file format data container of claim 19 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 192 bits.
 34. The .Zip file format data container of claim 19 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 256 bits.
 35. The .Zip file format data container of claim 19 wherein said symmetrically encrypting said data file uses an AES encryption encoding operation.
 36. The .Zip file format data container of claim 19 wherein said symmetrically encrypting said data file uses a 3DES encryption encoding operation.
 37. A method of placing data in a data container, said method including: receiving a data file; generating a first symmetric key from random data; symmetrically encrypting said data file using said first symmetric key to form and encrypted data file; generating a second symmetric key; symmetrically encrypting said first symmetric key using said second symmetric key to form second symmetric key data; generating a third symmetric key; symmetrically encrypting said first symmetric key using said third symmetric key to form third symmetric key data; and placing said encrypted data file, said second symmetric key data, and said third symmetric key data in a data container, wherein said data container is designed for containing compressed files.
 38. The method of claim 37 further including: compressing said data file before symmetrically encrypting said data file.
 39. The method of claim 38 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.
 40. The method of claim 38 wherein said compressing employs a Deflate-type data compression algorithm.
 41. The method of claim 38 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 42. The method of claim 37 wherein said data file is not compressed before symmetrically encrypting.
 43. The method of claim 37 wherein at least part of one of said second symmetric key and said third symmetric key is composed of random data.
 44. The method of claim 43 wherein at least part of said second symmetric key is composed of a first set of random data and at least part of said third symmetric key is composed of a second set of random data.
 45. The method of claim 44 wherein said first set of random data is not equal to said second set of random data.
 46. The method of claim 37 wherein said at least part of one of said second symmetric key and said third symmetric key is received from a user.
 47. The method of claim 46 wherein said at least part of one of said second symmetric key and said third symmetric key is a password.
 48. The method of claim 47 wherein at least part of said second symmetric key is a first password and at least part of said third symmetric key is a second password
 49. The method of claim 48 wherein said first password is not equal to said second password.
 50. The method of claim 37 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 128 bits.
 51. The method of claim 37 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 192 bits.
 52. The method of claim 37 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 256 bits.
 53. The method of claim 37 wherein said symmetrically encrypting said data file uses an AES encryption encoding operation.
 54. The method of claim 37 wherein said symmetrically encrypting said data file uses a 3DES encryption encoding operation.
 55. The method of claim 37 wherein said data container is constructed in accordance with a .Zip file format.
 56. A data container including: an encrypted data file, said data file encrypted using a first symmetric key, wherein said first symmetric key is generated from random data; second symmetric key data, said second symmetric key data generated from a second symmetric key used to symmetrically encrypt said first symmetric key; and third symmetric key data, said third symmetric key data generated from a third symmetric key used to symmetrically encrypt said first symmetric key, wherein said data container is designed for containing compressed files.
 57. The data container of claim 56 wherein said data file is compressed prior to symmetric encryption.
 58. The data container of claim 57 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.
 59. The data container of claim 57 wherein said compressing employs a Deflate-type data compression algorithm.
 60. The data container of claim 57 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 61. The data container of claim 56 wherein said data file is not compressed before symmetric encryption.
 62. The data container of claim 56 wherein at least part of one of said second symmetric key and said third symmetric key is composed of random data.
 63. The data container of claim 62 wherein at least part of said second symmetric key is composed of a first set of random data and at least part of said third symmetric key is composed of a second set of random data.
 64. The data container of claim 63 wherein said first set of random data is not equal to said second set of random data.
 65. The data container of claim 56 wherein said at least part of one of said second symmetric key and said third symmetric key is received from a user.
 66. The data container of claim 65 wherein said at least part of one of said second symmetric key and said third symmetric key is a password.
 67. The data container of claim 66 wherein at least part of said second symmetric key is a first password and at least part of said third symmetric key is a second password
 68. The data container of claim 67 wherein said first password is not equal to said second password.
 69. The data container of claim 56 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 128 bits.
 70. The data container of claim 56 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 192 bits.
 71. The data container of claim 56 wherein at least one of said first symmetric key, said second symmetric key and said third symmetric key has a key length of at least 256 bits.
 72. The data container of claim 56 wherein said symmetrically encrypting said data file uses an AES encryption encoding operation.
 73. The data container of claim 56 wherein said symmetrically encrypting said data file uses a 3DES encryption encoding operation.
 74. The data container of claim 56 wherein said data container is constructed in accordance with a .Zip file format.
 75. A method of placing data in a .Zip file format data container, said method including: receiving a data file; symmetrically encrypting said data file using a first symmetric key; generating first symmetric key data based on said first symmetric key; symmetrically encrypting said data file using a second symmetric key; generating second symmetric key data based on said second symmetric key; and placing said data file encrypted using said first symmetric key, said data file encrypted using said second symmetric key, said first symmetric key data, and said second symmetric key data in a data container, wherein said data container is constructed in accordance with a .Zip file format.
 76. The method of claim 75 further including: compressing said data file before symmetrically encrypting said data file.
 77. The method of claim 76 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.
 78. The method of claim 76 wherein said compressing employs a Deflate-type data compression algorithm.
 79. The method of claim 76 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 80. The method of claim 75 wherein said data file is not compressed before symmetrically encrypting.
 81. The method of claim 75 wherein at least part of one of said first symmetric key and said second symmetric key is composed of random data.
 82. The method of claim 81 wherein at least part of said first symmetric key is composed of a first set of random data and at least part of said second key is composed of a second set of random data.
 83. The method of claim 82 wherein said first set of random data is not equal to said second set of random data.
 84. The method of claim 75 wherein said at least part of one of said first symmetric key and said second symmetric key is received from a user.
 85. The method of claim 84 wherein said at least part of one of said first symmetric key and said second symmetric key is a password.
 86. The method of claim 85 wherein at least part of said first symmetric key is a first password and at least part of said second key is a second password
 87. The method of claim 86 wherein said first password is not equal to said second password.
 88. The method of claim 75 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 128 bits.
 89. The method of claim 75 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 192 bits.
 90. The method of claim 75 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 256 bits.
 91. The method of claim 75 wherein at least one of symmetrically encrypting said data file using said first symmetric key and symmetrically encrypting said data file using said second symmetric key uses an AES encryption encoding operation.
 92. The method of claim 75 wherein at least one of symmetrically encrypting said data file using said first symmetric key and symmetrically encrypting said data file using said second symmetric key uses an 3DES encryption encoding operation.
 93. A .Zip file format data container including: a first symmetrically encrypted data file, said first symmetrically encrypted data file formed by symmetrically encrypting a data file; and a second symmetrically encrypted data file, said second symmetrically encrypted data file formed by symmetrically encrypting said data file; a first set of symmetric key data associated with said first symmetrically encrypted data file data file, said first set of symmetric key data generated from a first symmetric key used to symmetrically encrypt said data file; and a second set of symmetric key data associated with said data file, said second set of symmetric key data generated from a second symmetric key used to symmetrically encrypt said data file, wherein said data container is constructed in accordance with a .Zip file format.
 94. The .Zip file format data container of claim 93 wherein said data file is compressed prior to symmetric encryption.
 95. The .Zip file format data container of claim 94 wherein said data file is compressed using a Lempel-Ziv (LZ)-type data compression algorithm.
 96. The .Zip file format data container of claim 94 wherein said data file is compressed using a Deflate-type data compression algorithm.
 97. The .Zip file format data container of claim 94 wherein said data file is compressed using a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 98. The .Zip file format data container of claim 93 wherein said data file is not compressed before symmetric encryption.
 99. The .Zip file format data container of claim 93 wherein at least part of one of said first symmetric key and said second symmetric key is composed of random data.
 100. The .Zip file format data container of claim 99 wherein at least part of said first symmetric key is composed of a first set of random data and at least part of said second key is composed of a second set of random data.
 101. The .Zip file format data container of claim 100 wherein said first set of random data is not equal to said second set of random data.
 102. The .Zip file format data container of claim 93 wherein said at least part of one of said first symmetric key and said second symmetric key is received from a user.
 103. The .Zip file format data container of claim 102 wherein said at least part of one of said first symmetric key and said second symmetric key is a password.
 104. The .Zip file format data container of claim 103 wherein at least part of said first symmetric key is a first password and at least part of said second key is a second password
 105. The .Zip file format data container of claim 104 wherein said first password is not equal to said second password.
 106. The .Zip file format data container of claim 93 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 128 bits.
 107. The .Zip file format data container of claim 93 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 192 bits.
 108. The .Zip file format data container of claim 93 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 256 bits.
 109. The .Zip file format data container of claim 93 wherein at least one of said first symmetric key data and said second symmetric key data is derived from a symmetric key used in an AES encryption encoding operation.
 110. The .Zip file format data container of claim 93 wherein at least one of said first symmetric key data and said second symmetric key data is derived from a symmetric key used in a 3DES encryption encoding operation.
 111. The .Zip file format data container of claim 93 wherein said data file is encrypted using an AES encryption encoding operation.
 112. The .Zip file format data container of claim 93 wherein said data file is encrypted using a 3DES encryption encoding operation.
 113. A method of placing data in a data container, said method including: receiving a data file; symmetrically encrypting said data file using a first symmetric key; generating first symmetric key data based on said first symmetric key; symmetrically encrypting said data file using a second symmetric key; generating second symmetric key data based on said second symmetric key; placing said data file encrypted using said first symmetric key, said data file encrypted using said second symmetric key, said first symmetric key data, and said second symmetric key data in a data container, wherein said data container is designed for containing compressed files.
 114. The method of claim 113 further including: compressing said data file before symmetrically encrypting said data file.
 115. The method of claim 114 wherein said compressing employs a Lempel-Ziv (LZ)-type data compression algorithm.
 116. The method of claim 114 wherein said compressing employs a Deflate-type data compression algorithm.
 117. The method of claim 114 wherein said compressing employs a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 118. The method of claim 113 wherein said data file is not compressed before symmetrically encrypting.
 119. The method of claim 113 wherein at least part of one of said first symmetric key and said second symmetric key is composed of random data.
 120. The method of claim 119 wherein at least part of said first symmetric key is composed of a first set of random data and at least part of said second key is composed of a second set of random data.
 121. The method of claim 120 wherein said first set of random data is not equal to said second set of random data.
 122. The method of claim 113 wherein said at least part of one of said first symmetric key and said second symmetric key is received from a user.
 123. The method of claim 122 wherein said at least part of one of said first symmetric key and said second symmetric key is a password.
 124. The method of claim 123 wherein at least part of said first symmetric key is a first password and at least part of said second key is a second password
 125. The method of claim 124 wherein said first password is not equal to said second password.
 126. The method of claim 113 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 128 bits.
 127. The method of claim 113 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 192 bits.
 128. The method of claim 113 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 256 bits.
 129. The method of claim 113 wherein at least one of symmetrically encrypting said data file using said first symmetric key and symmetrically encrypting said data file using said second symmetric key uses an AES encryption encoding operation.
 130. The method of claim 113 wherein at least one of symmetrically encrypting said data file using said first symmetric key and symmetrically encrypting said data file using said second symmetric key uses an 3DES encryption encoding operation.
 131. The method of claim 113 wherein said data container is constructed in accordance with a .Zip file format.
 132. A data container including: a first symmetrically encrypted data file, said first symmetrically encrypted data file formed by symmetrically encrypting a data file; and a second symmetrically encrypted data file, said second symmetrically encrypted data file formed by symmetrically encrypting said data file; a first set of symmetric key data associated with said first symmetrically encrypted data file data file, said first set of symmetric key data generated from a first symmetric key used to symmetrically encrypt said data file; and a second set of symmetric key data associated with said data file, said second set of symmetric key data generated from a second symmetric key used to symmetrically encrypt said data file, wherein said data container is designed for containing compressed files.
 133. The data container of claim 132 wherein said data file is compressed prior to symmetric encryption.
 134. The data container of claim 133 wherein said data file is compressed using a Lempel-Ziv (LZ)-type data compression algorithm.
 135. The data container of claim 133 wherein said data file is compressed using a Deflate-type data compression algorithm.
 136. The data container of claim 133 wherein said data file is compressed using a Burrows-Wheeler Transform (BWT)-type data compression algorithm.
 137. The data container of claim 132 wherein said data file is not compressed before symmetric encryption.
 138. The data container of claim 132 wherein at least part of one of said first symmetric key and said second symmetric key is composed of random data.
 139. The data container of claim 138 wherein at least part of said first symmetric key is composed of a first set of random data and at least part of said second key is composed of a second set of random data.
 140. The data container of claim 139 wherein said first set of random data is not equal to said second set of random data.
 141. The data container of claim 132 wherein said at least part of one of said first symmetric key and said second symmetric key is received from a user.
 142. The data container of claim 141 wherein said at least part of one of said first symmetric key and said second symmetric key is a password.
 143. The data container of claim 142 wherein at least part of said first symmetric key is a first password and at least part of said second key is a second password
 144. The data container of claim 143 wherein said first password is not equal to said second password.
 145. The data container of claim 132 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 128 bits.
 146. The data container of claim 132 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 192 bits.
 147. The data container of claim 132 wherein at least one of said first symmetric key and said second symmetric key has a key length of at least 256 bits.
 148. The data container of claim 132 wherein at least one of said first symmetric key data and said second symmetric key data is derived from a symmetric key used in an AES encryption encoding operation.
 149. The data container of claim 132 wherein at least one of said first symmetric key data and said second symmetric key data is derived from a symmetric key used in a 3DES encryption encoding operation.
 150. The data container of claim 132 wherein said data container is constructed in accordance with a .Zip file format.
 151. The data container of claim 132 wherein said data file is encrypted using an AES encryption encoding operation.
 152. The data container of claim 132 wherein said data file is encrypted using a 3DES encryption encoding operation. 